1. Field of the Invention
This invention relates to pressure applying rolls and, more particularly, to controlled deflection rolls comprising an inner non-rotative shaft having a roll shell journaled about it, the inner shaft having hydrostatic bearings directed against the inner surface of the roll shell.
2. Prior Art
This invention is generally related to copending U.S. applications, Ser. No. 583,860, filed June 4, 1975 and Ser. No. 658,619, filed Feb. 17, 1976, both being assigned to the assignee of the present invention. The first application discloses an arrangement to externally bend the inner non-rotating shaft of the deflection roll wherein deflection sensors control the amount of bending, the inner shaft bending in a manner to counter any deflection of the roll shell. The latter application discloses toroidally shaped flexible membrane members disposed on the radially outer end of shell supporting members which are themselves disposed in the inner non-rotative shaft so as to press the membrane toward the outer shell. The toroidally shaped membrane provides a conformable hydrostatic bearing acting against the inner surface of the outer shell to uniformly support the outer shell and to reduce or eliminate deflections caused by external loads or to deflect the shell in a predetermined way.
An earlier patent, also assigned to the assignee of the present invention, is U.S. Pat. No. 3,587,152, which involves a controlled deflection roll having one or more radially acting pressure applying pistons. Each piston has a pad on its radially outer end with a curvilinear surface that supports the inner surface of the roll shell with pressurized fluid providing a hydrostatic bearing therebetween.
U.S. Pat. No. 3,846,883 discloses a piston and hydrostatic bearing shoe arrangement for deflection rolls. The shoe is pivotally mounted on the outer end of the piston, the piston being held in a radially slidable relationship with the non-rotating inner shaft.
Another recent U.S. Pat. No. 3,879,827, discloses a roll for a rolling mill wherein isolated arrays of hydrostatic bearings may have a larger bearing force at the middle of the roll shell. A further example of the prior art is shown in U.S. Pat. No. 3,802,044 wherein a piston has a hydrostatic bearing interface with a roll shell, the bearing being tiltable to a slight degree and is fed with pressurized fluid from a servomotor, the piston being floatable within the nonrotative shaft. Foreign prior art includes British Patent No. 641,466 and Canadian Patent No. 976,031 which disclose pressure roller arrangements. U.S. Pat. No. 3,346,924, assigned to the present assignee, discloses a bladder type force applicator, not used, however, for deflection rolls, but for injection molding machines.
It is seen, therefore, that the prior art encompasses a number of approaches to the problem of providing support for a deflectable roll shell, and the like. Much of the prior art is comprised of unduly complicated geometry of their pistons and some of the prior art has the potential disadvantage of being unstable during operating conditions, particularly if large deflections of the roll shell are encountered, which some art would not be able to correct. None of the art teaches the concept of pressurizable membranes disposed radially inwardly of radially movable pistons, the pistons themselves being permitted a longitudinal pivoting motion in a slotted stationary shaft.